A federal judge today signed off on subpoenas to various businesses associated with President Trump. This is part of a lawsuit alleging that Trump violated the anti-corruption Emoluments clauses in the constitution. NPR's Peter Overby reports.

PETER OVERBY, BYLINE: The lawsuit comes from the attorneys general of Maryland and the District of Columbia. Maryland AG Brian Frosh said the documents being sought have to do with the Trump Hotel in the Old Post Office building near the White House. It's become a magnet for Trump's political allies and for some foreign diplomats, which raises the question of emoluments, gifts to the president which the Constitution prohibits from foreign and state governments. Frosh said the subpoenas target three questions.

BRIAN FROSH: Which foreign governments and which domestic governments are paying The Trump Post Office Hotel? Then, where's it going? And how is the Trump Hotel affecting the hospitality industry in D.C. and in Maryland?

OVERBY: Subpoenas went to the Trump companies that own and operate the hotel, to the umbrella company, the Trump Organization and to the trust that Trump set up in a bid to insulate himself from issues like this one. Other subpoenas went to the General Services Administration, which leases the Old Post Office building to Trump's companies, and to the IRS. Frosh said they're not asking the IRS for Trump's tax returns, another hot-button issue. But...

FROSH: The information they have about the Trump entities would be very useful to us.

OVERBY: The timing of the subpoenas could be troublesome. The documents would be coming in and some of them becoming public in late 2019 as the presidential primaries are heating up. Don Kettl is a political scientist at the University of Texas.

DON KETTL: In itself, it may not be a big deal. But what it may do is to reinforce a broader story, a broader narrative about the first family's use of its official position to line their own personal pockets.